X is for A and X' is for B. It could be the case, although that's not simple and sounds ad-hoc. The other interpretation I mentioned is simpler and also it could be. Not clear.That means that those who are registered and those who are notified count to 100,000 together.
More is here because typically it is about 106000-110000. Not because it is 200000 with dependents.
And less than half means that for more than 100,000 family members there are only 50,000 visas. Less than half of more than 100,000
But sometimes less than 100,000 winners in fact. Your explanation sounds ad-hoc. 200,000 with derivatives is always more than 100,000 and always less than half.
Not clear....